Generally, electrostatographic copying, image production or reproduction is performed in cycles for example by exposing an image of an original document onto a substantially uniformly charged photoreceptive member. The photoreceptive member has a photoconductive layer. Ordinarily, exposing the charged photoreceptive member with the image discharges areas of the photoconductive layer corresponding to non-image areas of the original document, while maintaining the charge in the image areas. In discharge area development, the reverse is true where the image areas are the discharged areas and the non-image areas are the charged areas. Thus in either case, a latent electrostatic image of the original document is created on the photoconductive layer of the photoreceptive member.
Charged developing material is subsequently deposited on the photoreceptive member to develop the latent electrostatic image areas. The developing material may be a liquid material or a powder material. The charged developing material is attracted to the charged image areas on the photoconductive layer. This attraction develops the latent electrostatic image into a visible toner image. The visible toner image is then transferred from the photoreceptive member, either directly or after an intermediate transfer step, to a copy sheet or other support substrate as an unfused toner image which is then heated and permanently affixed to the copy sheet, resulting in a reproduction or copy of the original document. In a final step, the photoconductive surface of the photoreceptive member is cleaned to remove any residual developing material in order to prepare it for successive imaging cycles.
Following is a discussion of prior art, incorporated herein by reference, which may bear on the patentability of the present disclosure. In addition to possibly having some relevance to the question of patentability, these references, together with the detailed description to follow, are intended to provide a better understanding and appreciation of the present disclosure.
U.S. Pat. No. 7,278,699 issued Oct. 9, 2007 to Drake et al. and entitled “Enhanced printer reliability using extra print module” discloses methods and apparatus for extending the reliability and usefulness of a fullwidth printhead by providing a redundant temporary replacement printhead module that can be positioned to compensate for missing or faulty jet nozzles. In order to take advantage of a single extra printhead module and to be able to compensate for more than a single failed nozzle, the replacement module is mounted on a separate translating x-axis and preferably provided with roll adjustment along another axis so that an effective spacing of nozzles in the replacement module can be adjusted to align with detected defective nozzles. The fullwidth printhead is formed from at least one array of smaller printhead modules. The arrays may be offset by a non-integer spacing interval of the individual nozzles. For example, if the nozzle spacing is S, the offset may be S/2. By virtue of the x-translation and roll capabilities, a single replacement module can accommodate replacement of one or several defective nozzles spaced closer together than the total length L of the replacement module, even if the defective nozzle(s) are located on different printhead modules and have a non-integer spacing.
U.S. Pat. No. 7,274,883 issued Sep. 25, 2007 to Evans and entitled “Hybrid printer and related system and method” discloses a hybrid printing assembly that includes a first printing subassembly operable to produce a first pattern on a medium, and a second printing subassembly operable to produce a second pattern on the medium.
U.S. Pat. No. 6,421,133 issued Jul. 16, 2002 to Kasai et al. and entitled “Hybrid printer, printer mounting base and printer that is mountable on printer mounting base” discloses a hybrid printer includes a first printer, a second printer and a printer mounting base capable of mounting the first and second printers. The first printer has a first printing section for printing on a first recording paper, a first transfer path for transferring the first recording paper to the first printing section, a first base having the first transfer path formed thereon, and a first cantilever for supporting the first printing section above the first base. The second printer has a second printing section for printing on a second recording paper. The printer mounting base has a second base, a second transfer path formed on the second base and a second cantilever fixed to the second base. The second printer is mountable on the second cantilever of the printer mounting base. The printer mounting base is mountable in the rear of the first printer, and the second transfer path is disposed on an extension line of the first transfer path and continuous to the first transfer path when the printer mounting base is mounted on the first printer.
U.S. Pat. No. 5,911,527 issued Jun. 15, 1999 to Aruga et al. and entitled “Hybrid printer device equipped with a plurality of printing mechanisms and control method therefore” discloses a hybrid printer has mounted thereon a plurality of printing mechanisms and error processing appropriate to the respective printing mechanisms with differing functions and appropriate to the printing paper can be performed. Thermal printer state detector 65 and wire dot printer state detector 66 are provided which have the capability of detecting the respective states of thermal printing mechanism 10 and wire dot printing mechanism 20 mounted on hybrid printer 1. Further, printing mechanism selector 71 is capable of determining the printing mechanism selected from command data indicating the type paper. This makes it possible for state determination member 72 to know the error status of each printing mechanism and to determined which printing mechanism is in operation, and therefore it is possible to quickly perform error processing appropriate to the printing mechanism.
Conventionally, it is well known to provide printing systems that include one or more modules (xerographic modules) that perform electrostatographic copying, image production or reproduction as described above. As is also well known, such xerographic modules include limited components and use limited life materials, and so their operation has to be stopped or interrupted from time to time in order to replace such components or replenish such materials.
There therefore has been a need for printing systems that offer increasingly more and more uninterrupted long life along with other benefits.